firstratetm generator cost - powerworld · scott r. dahman, p.e. [email protected] 2001 south...

Scott R. Dahman, [email protected]://www.powerworld.com

2001 South First StreetChampaign, Illinois 61820+1 (217) 384.6330

FirstRateTM Generator Cost Models

PowerWorld Client ConferenceFebruary 23, 2016

2© 2016 PowerWorld CorporationFirstRate Generator Cost Models

• Motivation and Background• FirstRateTM Cost Model Source Data• FirstRateTM Limitations• Demo

Outline


• Automatic Generation Control (AGC) is a Simulator feature with several variants:– Participation Factor– Injection Group– Optimal Power Flow– Economic Dispatch– Area Slack

• Most of these can be applied to an Area, Super Area, or entire Island

Motivation and Background


• Power flow assumes constant frequency and balance between load and generation

• The key role of AGC (as a software feature) is to satisfy the Area Control Error (ACE) constraint for Islands, Areas, or Super Areas

• ACE = Generation – (Load + Losses + Scheduled Exports)

• Ideally ACE = 0 for all Areas and Super Areas on control

• ACE must be zero for all Islands (Island Slack or “Swing Bus” enforces this constraint)

AGC


• Defined with the power flow case• Every bus, generator, and load is assigned to exactly 1 area– Generators and loads are typically assigned to the same area as their terminal buses, but may differ

• Every Area on AGC has 1 ACE constraint

Areas


• Simulator object for aggregating Areas• Each Area can belong to at most one Super Area• Useful for ISO modeling• ACE constraints for individual Areas that are part of a Super Area are ignored– Replaced with a single ACE constraint for the Super Area

– Transactions (imports/exports) between Areas that are part of the Super Area and external Areas or Super Areas are aggregated

Super Areas


• Area Slack is commonly used in other software, but often degenerates to manual control

• If you make an adjustment to the case that affects ACE and the Area Slack generator moves too much, you manually adjust one or more other generators

• With other AGC methods, the software typically adjusts multiple generators and enforces limits

Area Slack Control


• Participation Factor Control is a means of allowing many generators in an Area, Super Area, or Island, to adjust to maintain ACE

• Individual units must have AGC=YES and a non‐zero participation factor to contribute

• ERCOT Example: transfer 200 MW from area 905 to area 908 (CPS Energy → AEP Texas Central Company)

Participation Factor Control


Difference Flows:200 MW Transfer


• Optimal Power Flow (OPF) seeks to meet ACE with minimal cost, subject to transmission constraints

• Can be applied to Area or Super Area• Most significant cost component is usually generation cost

• Generator Cost Models are needed as OPF inputs• PowerWorld can provide basic cost model parameters from public sources, formatted to import directly to FERC 715 planning models– Sold as “FirstRate” subscription service through Energy Visuals, Inc. (a PowerWorld affiliate)

– http://www.energyvisuals.com/products/firstrate.html

Optimal Power Flow


• Updated monthly with issue of US Energy Information Administration (EIA) generator data– Survey‐Level Detailed Data Files at http://www.eia.gov/electricity/data/detail‐data.html

• Formats for use with PowerWorld Simulator– Microsoft Excel spreadsheet– Simulator auxiliary file format

• Source Data mapped to power system key fields– Bus Number + Generator ID– Bus Name_NominalKV + Generator ID (not a strict key)

FirstRate Cost Models


• Form 923– Average heat rate– Cost and quantity of fuels

• Electric Power Monthly– Summary‐level information to help estimate withheld cost information

– Planned additions and retirements• Form 860

– Unit‐level fuel and prime mover– Geo‐coordinates

EIA Sources


• Total generator operating cost is modeled using cubic function

Ci(Pgi) = Fi + (Ai + BiPgi + Ci(Pgi)2+Di(Pgi)3) * fc + VOMPgi

Generator Cost Model: Cubic

Units are$ / hour

Variable O&M (VOM)Fuel cost (fc)


• Formulated like bids, with one or more breakpoints and associated costs

Generator Cost Model:Piecewise Linear

Linear cost curve breakpoints and costs


• Uses Simulator’s Cubic form, with only the linear term populated

• Fuel Cost and Variable O&M are also includedCi(Pgi) = (Bi * fc + VOM) * Pgi

FirstRate Sample Model

Average Heat Rate(MBtu/MWh)

Fuel Cost ($/MBtu)

Variable O&M($/MWh)


• Oklaunion Unit 1, Wilbarger County, TX

• Average Heat Rate: 10.34 MBtu/MWh

• Other Cubic Model terms are zero

• Fuel Cost and Variable O&M

FirstRate Sample Model


Other FirstRate Information

Plant Name and Operator, Fuel Type, and Unit (prime mover) Type


• Oklaunion coal purchases in January 2015, from the EIA source spreadsheet:

• FirstRate incorporates the last 12 months of available data (rolling, with each update)

EIA Form 923: Fuel Cost


• Oklaunion fuel consumption and MWh output

• FirstRate incorporates the last calendar year of available data

EIA Form 923: Heat Rate


• Fuel consumption and net generation are generally available

• Cost of fuels is not publicly available– FirstRate compiles averages from the most complete set of comparable characteristics for each: fuel type, prime mover, plant state, fuel source state, mine type, purchase type (contract vs. spot market), etc.

– If these are not available, use state, regional, or national average by broad fuel class (coal, natural gas, petroleum, etc.)

Non‐Regulated Plants


• Provides broad national, state, and regional‐level averages for utility and non‐utility plants

EIA Electric Power Monthly


• Martin Lake Unit 1– Sub‐bituminous purchased from WY on contract– Lignite purchased from TX on contract and spot market

• Compare to average price paid by Texas utility plants with similar source characteristics:

Non‐Regulated Plant Example


• Also incorporate ratio of average non‐utility price paid to utility price paid to estimate

• Compute weighted average cost of all types of coal purchases

• Distillate fuel oil is a secondary source– Used for les that 1% of MWh output– Ignored by FirstRate

Non‐Regulated Plant Example


• Removal of statistical outliers– Could be caused by data entry errors, misplaced decimals, wrong units, etc.

– Averages and standard deviations are considered for each fuel and prime mover type, and within each plant

Data Processing


• Wind, solar, and hydro units– do not have fuel costs or heat rates– Cost Model field is set to “None” in FirstRate

• Combined cycle units have uniform figures for all components– Simulator does not have algorithm to coordinate dispatch of

combustion turbine and steam units– Key result for OPF is total output of all units

• No explicit source for plant‐level Variable O&M in public EIA databases– Could be partially estimated from emissions– FirstRate uses industry averages

• Generally available only for FERC 715 planning models; maintenance challenges with other models– No persistent key fields– Generator information obscured or redacted

Limitations


• 15DSA_2016_WIN1_TPIT_Final_10152014 (2016 Winter Peak)

• OPF solutions without and with contingency constraints

Demo: ERCOT Model


OPF Solution: Base


OPF Solution:Contingency Constraints


• Download sample files and other documentation at http://www.powerworld.com/services/generator‐cost‐models

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